This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Prions are infectious proteinaceous particles which cause fatal neurodegenerative diseases. PrP the predominant protein within the infectious particles is a glycolipid membrane anchored protein. Removing the glycolipid induces large amounts of infectious aggregates to form within the brain. Using nitrogen isotope incorporation I want to investigate the rate of turnover within the aggregates formed from this soluble PrP isoform. Using the change in isotopic distribution of purified protein over time I will be able to calculate a turnover rate for the aggregate. The mass spec facility will assist in the determination of the isotope ratio for these proteins.